1. Technical Field
The disclosure relates to a display apparatus and a control method thereof, and, in particular, to a liquid crystal display (LCD) apparatus and an image control method thereof.
2. Related Art
Liquid crystal display (LCD) apparatuses have the advantages of low power consumption, low generated heat, lighted weight and non-radiative property, so that the LCDs have been used in various electronic products and gradually replaced the conventional cathode ray tube (CRT) display apparatus.
However, because the LCD apparatus has a multi-layer structure, the light outputted from the backlight module must penetrate through many optical films and a liquid crystal layer, so that the problem of the optical loss is very serious. Usually, the light finally outputted from the surface of the liquid crystal panel is only equal to a small fraction of the light outputted from the backlight source. Therefore, the LCD apparatus usually has the problem of insufficient brightness.
Regarding to this problem, a conventional solution is to add a white-light filter unit to the tricolor (RGB) filter unit in each pixel so that the light output amount of the white backlight is increased and the pixel brightness is increased. FIG. 1 is a schematic illustration showing the comparison of characteristics according to the conventional method (solid line) and conventional improvement method (broken line), wherein each characteristic represents a relationship between the brightness and the color saturation. As shown in FIG. 1, the brightness of the pixel utilizing the conventional improvement method is significantly increased when the pixel displays the tricolor mixture. However, when the displayed light of the pixel is close to monochromatic light (i.e. red, green or blue light), the brightness of the pixel utilizing the conventional improvement method is inversely lower than that utilizing the conventional method.
This is because the white backlight emitted from the white-light filter unit cannot become the gain for the displayed light when the displayed light approximates to monochromatic light. Inversely, the output amount of the monochromatic light is decreased because the area of the monochromatic filter unit is reduced. Thus, when the monochromatic light is being displayed, the brightness of the pixel utilizing the conventional improvement method is inversely lower than that utilizing the conventional method. Consequently, the brightness variation of the pixel utilizing the conventional improvement method is much greater than that utilizing the conventional method.
Therefore, it is important to provide a LCD apparatus with the enhanced display brightness and stable brightness variation, and an image control method thereof.